1. Field of the Invention
The invention relates to a method of operating a combined installation formed from a gas turbine group and a steam turbine installation, and an appliance for carrying out the method.
2. Discussion of Background
It is generally known that the combustion air required in the gas turbine process is provided by compressors. Part of the compressor air is frequently branched off in order to contribute to the cooling of the gas turbine blading.
The latter, however, is only possible if the compressor air is brought to a sufficiently low temperature because otherwise the cooling becomes questionable. In addition, high combustion air temperatures lead to difficulties in the maintenance of low oxides of nitrogen figures (NO.sub.x) in the exhaust gas of the gas turbine.
Particularly in the case of modern high-power gas turbines, high combustion air compression ratios are necessary, i.e. it is necessary to supply particularly strongly compressed combustion air, and this has disadvantageous effects in the sense previously described.
Although it is already known art to reduce the temperature level of the compressed combustion air by cooling in one or, if need be, in a plurality of coolers--as a remedy for the problems mentioned above--the extraction of heat from the combustion air taking place in this case is unfavorable with respect to the efficiency of combined installations and can therefore hardly be recommended if, at the same time, the heat energy extracted is not utilized.